The term latex is intended to mean aqueous dispersions of polymer particles, as obtained by polymerization in emulsion.
Most latexes for flexible coatings are based on polymers which have a low glass transition temperature, denoted Tg. The films or coatings resulting from latexes of this type generally have a surface tack which is fairly high and therefore prohibitive for many applications, in particular because they accumulate dirt.
The most common solution for reducing the tack, apart from increasing the Tg at the sacrifice of flexibility, is to cross-link the films chemically or photochemically. This solution is not entirely satisfactory.
Another solution is described by U.S. Pat. No. 5 308 820. It consists in mixing a dispersion of a "hard" polymer which provides the low tack and a dispersion containing a "soft" polymer which provides flexibility.
Furthermore, films may be rendered hydrophobic, or their surface tension may be reduced, by adding hydrophobic polymers such as polymers containing silicone. However, these do not correct the tendency to accumulate dirt, because they have a low Tg and are oleophilic.
Another solution is to introduce fluoropolymers, as described in FR 2 725 721.
It therefore seems difficult, or even impossible to find a coating which, at the same time, is flexible, hydrophobic and has low tack.
The object of the invention is therefore to develop coatings which meet the criteria mentioned above.